Genetic determinism of prickles in rose

General Discussion
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See:

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Pesky recessives :]

Well, whatever the case, Bonica and Summer Wind are good at either reducing or eliminating prickles. I have some linebred Dortmund types bred with Bonica. Zero prickles – 7 years old now. One can see Meilland has also used Bonica in climbers for this exact reason.

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Rose without prickle: genomic insights linked to moisture adaptation

Abstract

Prickles act against herbivores, pathogens or mechanical injury, while also preventing water loss. However, whether prickles have new function and the molecular genetics of prickle patterning remain poorly explored. Here, we generated a high-quality reference genome assembly for ‘Basye’s Thornless’ (BT), a prickle-free cultivar of Rosa wichuraiana, to identify genetic elements related to stem prickle development. The BT genome harbors a high level of sequence diversity in itself and with cultivar ‘Old Blush’ (R. chinensis), a founder genotype in rose domestication. Inheritance of stem prickle density was determined and two QTL were identified. Differentially expressed genes in QTL were involved in water-related functions, suggesting that prickle density may hitchhike with adaptations to moist environments. While the prickle-related gene-regulatory-network (GRN) was highly conserved, the expression variation of key candidate genes was associated with prickle density. Our study provides fundamental resources and insights for genome evolution in the Rosaceae. Ongoing efforts on identification of the molecular bases for key rose traits may lead to improvements for horticultural markets.

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Jin-Yong Hu has a great sense of humor:

For long-term benefits, according to the fairy tales of Jacob L.K. Grimm and Wilhelm C. Grimm (1812, Little Brier-Rose) and Oscar Wilde (1888, The Nightingale and the Rose), respectively, landscapes of prickle-free roses should reduce fatalities in populations of male royalty and birds in the genus Luscinia.

So if I understand this paper correctly these folks have sequenced the full genome of Bayse’s Thornless to a completeness greater than 95% and compared the genome to a couple of reference genomes made from one of the stud China roses, Old Blush. Their intent seems to be to build up reference genomes of diploid roses that can be analyzed with statistical methods to tease out the multiple influences of the various gene loci that are dose-dependent (quantitative trait loci). In this case they focused on prickle expression and offer a couple of insights in that regard including a guess that prickles correlate with evolution in a humid environment because they confer a relatively higher degree of moisture and thermal barrier.

I have been working since last century with a cultivar (of Rosa moyesii ) that is completely thornless as well. The thornlessness is heritable. The catch is that R. moyesii is arguably octaploid, just about as deep into the polyploid jungle as is possible to get and so probably not very useful as a research subject based on the intent of the authors.

My copy is limping at the moment so not clone-able but I do have preserved pollen and dried stems if anyone wants to look at the genetics of it at the molecular level.